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  1. #1 Carb Pilot size advice 
    C-Moto Senior arancara's Avatar
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    Basically I fitted a Mikuni 30mm carb over the stock 26mm chinese carb, things do seem to be alot better, but I'm having starting issues, its been cold lately which hasn't helped. Going by the mikuni pilot jet I've read 20, is this correct, it seems too small, whereas my other stock carb has k38 size printed. Any idea's what size pilot would I roughly need so I can order a rough range of pilots to try work things out. I had slight starting issues on stock carb as well, but not this bad. Once warmed up things are smooth except on a cold day it still may stall very early into a journey.

    Thanks in advance

    Alex
    Lexmoto XTR-S 156FMI (156cc big bore) - 163FML Cams (+1mm lift) - Foam Filter - Sports Exhaust - 17T Sprocket - 110 Main Jet - PZ30 Carb - Aprillia RS Ignition Coil - Casoli CDI

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  2. #2 Re: Carb Pilot size advice 
    Senior C-Moto Guru Zorge's Avatar
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    I would say that pilot jet for that carb and 125 cc, must be at least 40 or 45.

    You mentioned that you have Colortune? Did you use it to check mixture at idle?
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  3. #3 Re: Carb Pilot size advice 
    Senior C-Moto Guru humanbeing's Avatar
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    According to http://item.taobao.com/item.htm?id=16060415301 (That city is the capital of clone carb) stock 2? = 35# measured by flowing machine.
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  4. #4 Re: Carb Pilot size advice 
    C-Moto Senior arancara's Avatar
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    With stock carb (26mm) on a 38 it was just lean.

    So I think 45 is needed if the mikuni one is a 35?
    Lexmoto XTR-S 156FMI (156cc big bore) - 163FML Cams (+1mm lift) - Foam Filter - Sports Exhaust - 17T Sprocket - 110 Main Jet - PZ30 Carb - Aprillia RS Ignition Coil - Casoli CDI

    My Project: http://xtrsproject.wordpress.com/
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  5. #5 Re: Carb Pilot size advice 
    C-Moto Senior arancara's Avatar
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    I'm between a 45 and 50 size at a guess as the carb is 33% bigger in area. Plus the choke butterfly has a drilled hole unlike the stock carb, what's people's advice from.experience?
    Lexmoto XTR-S 156FMI (156cc big bore) - 163FML Cams (+1mm lift) - Foam Filter - Sports Exhaust - 17T Sprocket - 110 Main Jet - PZ30 Carb - Aprillia RS Ignition Coil - Casoli CDI

    My Project: http://xtrsproject.wordpress.com/
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  6. #6 Re: Carb Pilot size advice 
    Senior C-Moto Guru Zorge's Avatar
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    One detail: is your foam air filter properly oiled? I ask that because I think I saw a photo on your blog. It looked to me, that this foam is dry.
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  7. #7 Re: Carb Pilot size advice 
    C-Moto Senior arancara's Avatar
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    Air filter is dry indeed, didn't think it needs to be oiled as I know on cars the oil plays havoc with the MAF sensors, I've never had to deal with carbs up until now.
    Lexmoto XTR-S 156FMI (156cc big bore) - 163FML Cams (+1mm lift) - Foam Filter - Sports Exhaust - 17T Sprocket - 110 Main Jet - PZ30 Carb - Aprillia RS Ignition Coil - Casoli CDI

    My Project: http://xtrsproject.wordpress.com/
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  8. #8 Re: Carb Pilot size advice 
    Senior C-Moto Guru humanbeing's Avatar
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    Quote Originally Posted by arancara View Post
    I'm between a 45 and 50 size at a guess as the carb is 33% bigger in area. Plus the choke butterfly has a drilled hole unlike the stock carb, what's people's advice from.experience?
    North American guys had more experience about Mikuni on Honda clone. http://chinariders.net/modules.php?n...=viewforum&f=1 had many good article . Pan-chinese (TW/ mainland) prefers Keihin .
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  9. #9 Re: Carb Pilot size advice 
    C-Moto Senior arancara's Avatar
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    Had a quick look on the link human, similar issues as me on the pilot, but I'm really confused with one thing, is a mikuni 20 a completely different size unit altogether? most of the lads have put a 25 one in on that forum and I've just placed an order for a 45 size... Are the jet sizes not standardized and is there a conversion chat between manufacturers as this has left me confused.
    Lexmoto XTR-S 156FMI (156cc big bore) - 163FML Cams (+1mm lift) - Foam Filter - Sports Exhaust - 17T Sprocket - 110 Main Jet - PZ30 Carb - Aprillia RS Ignition Coil - Casoli CDI

    My Project: http://xtrsproject.wordpress.com/
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  10. #10 Re: Carb Pilot size advice 
    Senior C-Moto Guru Zorge's Avatar
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    There is no sensors or something similar on your bike's intake system, so you can try to enrich mixture by increasing the resistance to air flow through the filter element by a simple oiling it. This "choking" is old two-stroker's technique, when you don't have carb that "doctor has prescribed" for your engine - maybe won't work for you, but why not to try? The only consequence can be additional degreasing of filter and greasy hands.

    Numbers at the jets can refer to, either the diameter of the hole, or flow through jet under certain conditions (I think this is Mikuni, an maybe Solex method of marking).

    Carb on your bike came with pilot jet marked 20, and my 50 cc tiller has Deni PZ-17 (Keihin clone) carb and pilot jet marked 35. So, do you see the logic?

    In short: if someone does not give proven setup that works, you're sentenced to a frustrating experiments.
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